Electrodeposition of NiW, NiWMo, and NiMo Alloy Thin Films ...Electrodeposition of NiW, NiWMo, and...

Electrodeposition of NiW, NiWMo, and

NiMo Alloy Thin Films and

NiW Nanowires

Tetiana Bairachna Master of Science

Thesis Defense

Scientific adviser: Prof. E. J. Podlaha-Murphy

Chemical Engineering Department

Northeastern University

Boston MA 02115

August 15, 2011

Outline

1. Motivation: Why NiW, NiWMo, and NiMo?

Why NiW nanowires?

2. Literature search: what has been done before?

3. Experimental

4. Results:

Electrodeposition of NiW, NiWMo, and NiMo alloys

Electrodeposition of NiW nanowires

Mechanical robustness of NiW nanowires

4. Conclusions

6. Acknowledgments

2

3

Motivation: Why NiW, NiWMo, and NiMo alloys?

Why NiW nanowires?

1. Why NiW, NiWMo, and NiMo alloys? Outstanding

functional properties:

- thermal resistance

- wear resistance

- corrosion resistance

- microhardness

- magnetic properties

- catalytic activity towards hydrogen evolution reaction

2. Why NiW nanowires?

- to investigate properties on the nanoscale level:

structure, morphology, robustness

- to create new composite material

Literature search: what has been done before?

Literature search: references on NiW and NiMo electrodeposition 1. , Electrodeposition of alloys, Academic Press, New York ( )

2. and D. Landolt, J. Electrochem Soc., 143 (3), 885 ( )

3. and L. Kahlenberg, Quart. Rev. Am. Electroplaters' Soc., 19 (9), 41 ( )

4. C. G. Fink and F. L. Jones, Trans. Electrochem. Soc., 59, 461 (1931)

5. L. N. Gol'tz and V. N. Kharlamov, Zhur. Prikl. Khim., 13, 1326 (1936)

6. M. L. Holt and L. E. Vaaler, J. Electrochem. Soc., 94, 50 (1948)

7. J. Kashima and F. Fukushima, J. Electrochem. Soc. Japan, 15, 33 (1947)

8. T. H. Fleisch, J. W. Zajac, and J. O. Schreiner, Appl. Surf. Sci., 26, 488 (1986)

9. T. F. Fransevich-Zabludovskaya, A. I. Zayats and V. T. Barchuk, Ukrain. Khim. Zhur., 25, 713 (1959)

10. A. T. Vas'ko, Electrochemistry of tungsten, Tekhnika, Kyiv (1969)

11. O. Younes and E. Gileadi, Electrochem. Solid St. Let., 3 (12), 543 (2000)

12. T. M. Sridhar, N. Eliaz, and E. Gileadi, Electrochem. Solid St. Lett., 8 (3), C58 (2005)

13. N. Tsyntsaru, S. Belevsky, A. Dikusar, and J. P. Celis, Trans. Inst. Metal Finish., 86 (6), 301 (2008)

14. V.Vasauskas, J. Padgurskas, R.Rukuiža, H.Cesiulis, J. P. Celis, D.Milcius, I.Prosycevas, Mechanika, 72 (4),

21 (2008)

15. M. Donten, H. Cesiulis, and Z. Stojek, Electrochim. Acta, 50 (6), 1405 (2005)

16. N. Atanassov, K. Gencheva, and M. Bratoeva, Plat. Surf. Finish., 84 (2), 67 (1997)

17. I. Mizushima, P. T. Tang, and H. N. Hansen, M. A. J. Somers, Electrochim. Acta, 51,

6128 (2006)

18. M.D. Obradovic, R.M. Stevanovic, and A.R. Despic, J. Electroanalyt. Chem., 552, 185 (2003)

19. V. Kublanovskii, O. Bersirova, Yu. Yapontseva, H. Cesiulis, and E. Podlaha-Murphy,

Prot. Met. Phys. Chem. Surf., 45 (5), 588 (2009)

20. M. R. Pavlov, N. V. Morozova, V. N. Kudriavtsev, Zaschita Metallov, 43 (5), 503 (2007)

21. T. Nenastina, , M. Ved, V. Shtefan, and M. Sakhnenko, Func. Mat., 14 (3), 395 ( ) 4

5

Literature search: NiW microstructures

Electrodeposition of NiW microposts*

* L. Namburi, Electrodeposition of Ni-W alloys into deep recesses, Thesis of Master of Science in

Chemical Engineering, B.Tech., Osmania University, 1999

Fig. 1. SEM image of a NiW micropost Fig. 2. SEM micrograph of Ni microposts

Electrolyte with NH4OH, pH 10

Temperature 70 oC

Recesses of 500 micron deep

Tungsten content less than 10 wt %

Goal – stronger Ni microposts

Fig. 3. SEM image of NiW microposts

Literature search: NiW nanostructures

6

Electrodeposition of CuNiW nanowires for magnetic applications*

* M. Gupta and , Electrodeposition of CuNiW alloys: thin films, nanostructured multilayers

and nanowires. J. Appl. Electrochem. 40 ( ) 1429-1439

Fig. 4. TEM image of multilayered

CuNiW nanowires Fig. 5. SEM micrograph of CuNiW

multilayers

Ammonia containing electrolyte, pH 8

Temperature 70oC

Highest tungsten content 33 wt.%

Alumina templates: 200 nm diameter and 60 µm length

Goals:

I. Determine conditions for depositing nanowires from thin

film NiW electrodeposition data

II. Develop conditions to deposit NiWMo thin films (not found

in literature) and compare to NiW and NiMo

III. Deposit NiW nanowires (not found in literature) and

investigate their robustness

7

Experimental'1

8

Electrodeposition into a

template: Whatman Nuclepore

Polycarbonate Track-Etch

Membrane

Potentiostat: Solartron SI

1287

Composition: XRF, Kevex

Omicron x-ray Fluorescence

Spectroscope

TEM and SEM Hummer sputtering system

Experimental’2

9

Au cathode Pt anode

SCE

Electrolyte:

Na2MeO4·2H2O 0.15 M

for NiW Me=W

for NiWMo Me=Mo+W

for NiMo Me=Mo

NiSO4·6H2O 0.1 M

Na3Cit 0.375 M

H3BO3 1 M

NaOH/H2SO4 for pH 7.0

Difference:

room temperature

no ammonia

polycarbonate membrane with pore size 10 to 100 nm

*Schematic from Maoshi Guan

Fig. 6. Schematic of the cell for the

electrodeposition of nanowires*

Cathode: gold film on the

bottom of the membrane,

Hummer sputtering system

Anode: Pt mesh

Reference electrode: SCE

Results

Part I

Electrodeposition of NiW, NiWMo, and

NiMo alloy thin films

Results: NiW alloy electrodeposition’1

W

Ni

Current efficiency

Fig. 8. Dependence of W and Ni

content in NiW alloys and current

efficiency in the range of applied

current densities of 10-700 mA/cm2

Fig. 7. Dependence of W and

Ni content in NiW alloys and

current efficiency

10

0

10

20

30

40

50

60

70

0 10 20 30 40 50 60

Co

mp

on

ent

con

ten

t, w

t %

Cu

rren

t ef

fici

ency

, %

Current density, mA/cm2

0

20

40

60

80

100

0 100 200 300 400 500 600 700 800

Co

mp

on

ent

con

ten

t, w

t %

Cu

rren

t ef

fici

ency

, %


Ni

W

Current efficiency

Higher j – lower W and CE

Results: NiW alloy electrodeposition’2

Fig. 11. Dependence of Log of partial current

density for Ni and W in NiW alloy

Fig. 10. Partial current densities for W and

Ni in NiW vs potential in the range of

applied current densities of 10-700 mA/cm2

Fig. 9. Partial current densities for W and

Ni in NiW alloy

0

0.4

0.8

1.2

1.6

2

0.8 1 1.2 1.4 1.6 1.8 2 2.2Par

tial

cu

rren

t d

ensi

ty, m

A/c

m2

Potential, -V vs SCE

2 5 10 20 30 40 50 Applied current density, mA/cm2

W

Ni

0

2

4

6

8

10

12

14

1 2 3 4 5 6 7Par

tial

cu

rren

t d

ensi

ty, m

A/c

m2

Potential, -V vs SCE 10 50 100/200/350/500/700

Applied current density, mA/cm2

Ni

W

2.5

2.8

3.1

3.4

3.7

4.0

4.3

0 1 2 3 4 5 6 7

Lo

g o

f p

arti

al c

urr

ent

den

sity

[A/c

m2]

Potential -E, V vs SCE

Ni

W

@ 20<j<100 mA/cm2 jW>jNi

@ j>100 mA/cm2 jNij>W

11

Results: NiWMo alloy electrodeposition. Mo:W=1:1

Fig. 12. Dependence of W, Ni, Mo, and Mo+W

content in NiWMo alloy on applied current

density. Mo:W=1:1

Fig. 14. Dependence of Log of partial

current density for W, Ni, and Mo in

NiWMo alloy vs potential. Mo:W=1:1

Fig. 13. Partial current densities for W,

Ni, and Mo in NiWMo alloy vs

potential. Mo:W=1:1

Mo+W in NiWMo > W in NiW

Mo > W

j for Mo, Ni, and W ↑ @ -E > 5

12

1

1.5

2

2.5

3

3.5

4

0 1 2 3 4 5 6

Lo

g o

f p

arti

al c

urr

ent

den

sity

[A/c

m2]


Mo

Ni

W

0

1

2

3

4

5

6

1 2 3 4 5 6

Par

tial

cu

rren

t d

ensi

ty, m

A/c

m2


10 50 100 200 350/500/700 Applied current density, mA/cm2

Mo

Ni

W

0

10

20

30

40

50

60

70

80

0 100 200 300 400 500 600 700 800

Co

mp

on

ent

con

ten

t, w

t %


W

Ni

Mo

Mo+W

Fig. 15. Dependence of W, Ni, Mo, and

Mo+W content in NiWMo alloy on applied

current density. Mo:W=1:3

Fig. 16. Partial current densities for W, Ni, and

Mo in NiWMo alloy vs potential. Mo:W=1:3

Fig. 17. Dependence of Log of partial

current density for W, Ni, and Mo in

NiWMo alloy vs potential . Mo:W=1:3

j for Mo, W, and Ni ↑@ -E >6 V

0

1

2

3

4

5

1 2 3 4 5 6 7 8

Par

tial

cu

rren

t d

ensi

ty, m

A/c

m2


10 50 100 200 350 500 700


Mo

Ni

W


0

10

20

30

40

50

60

70

80

0 100 200 300 400 500 600 700 800

Co

mp

on

ent

con

ten

t, w

t %


W

Ni

Mo

Mo+W

1

1.5

2

2.5

3

3.5

4

0 1 2 3 4 5 6 7 8

Lo

g o

f p

arti

al c

urr

ent

den

sity

[A/c

m2]


Mo

Ni

W

13

Fig. 18. Dependence of W, Ni, Mo, and

Mo+W content in NiWMo alloy on applied

current density. Mo:W=3:1

Fig. 19. Partial current densities for W, Ni,

and Mo in NiWMo alloy vs potential.

Mo:W=3:1


density for W, Ni, and Mo in NiWMo alloy vs

potential. Mo:W=3:1

Mo:W=3:1 gives higher Mo+W than

1:1 and 1:3


1

1.5

2

2.5

3

3.5

4

0 1 2 3 4 5 6 7 8

Lo

g o

f p

arti

al c

urr

ent

den

sity

[A/c

m2]


Mo

Ni

W

0

1

2

3

4

1 2 3 4 5 6 7 8

Par

tial

cu

rren

t d

ensi

ty,

mA

/cm

2

Potential, -V vs SCE 10 50 100 200 350 500 700


Mo

Ni

W

0

10

20

30

40

50

60

70

80

90

0 100 200 300 400 500 600 700 800

Co

mp

on

ent

con

ten

t, w

t %


Mo

Mo+W

Ni

W

14

Fig. 21. Dependence of W, Ni, and Mo content in

NiWMo alloy on the ratio of refractory metals

concentrations in the electrolyte.

c(Na2MoO4·2H2O) 0.0375, 0.075, and 0.1125. pH

5.0. Current density 100 mA/cm2. (Point

c(Mo)/c(W)=10 represents case with no W in the

solution)

Fig. 22. Dependence of deposition rate, deposition

potential, and current efficiency on the ratio of

refractory metals concentrations in the electrolyte.

c(Na2MoO4·2H2O) 0.0375, 0.075, and 0.1125. pH

5.0. Current density 100 mA/cm2. (Point

c(Mo)/c(W)=10 represents case with no W in the

solution)

Mo:W=3:1 gives about the same amount of Mo in NiWMo alloy as for NiMo

Mo:W ratio also influences current efficiency CE– the highest CE 4 % @ Mo:W 1:1

Results: NiWMo alloy electrodeposition. Comparison

0

20

40

60

80

100

0 2 4 6 8 10

Co

mp

on

ent

con

ten

t, w

t %

c(Mo)/c(W), M/M

Mo+W

Mo

Ni

W 1

1.5

2

2.5

3

3.5

4

4.5

0 2 4 6 8 10

Cu

rren

t ef

fici

ency

, %

Dep

osi

tio

n r

ate,

mk

m/h

ou

r

Dep

osi

tio

n p

ote

nti

al, -V

c(Mo)/c(W), M

Deposition potential

Deposition rate

Current efficiency

15

Results: The behavior of W in NiW and NiWMo alloy

Fig. 23. Partial current densities for W vs

potential for NiW and NiWMo alloys (see Fig.

26 for detailed dependences for W in NiWMo

alloy)

Fig. 24. Partial current densities for W vs

potential for NiWMo alloy with varied

Mo:W ratio in the electrolyte

jW in NiW >> jW in NiWMo alloy → Mo inhibits W reduction

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0 1 2 3 4 5 6 7 8

Par

tial

cu

rren

t d

ensi

ty, m

A/c

m2


Mo:W=1:3

Mo:W=1:1 Mo:W=3:1

0

0.5

1

1.5

2

2.5

0 1 2 3 4 5 6 7 8

Par

tial

cu

rren

t d

ensi

ty, m

A/c

m2


W in NiW

W in NiWMo

16

Results: NiMo alloy electrodeposition

Fig. 25. Dependence of Ni and Mo content in

NiMo alloy on current density. pH 7.0

Fig. 26. Partial current densities for Mo and

Ni in NiMo alloy vs potential

Amount of Mo (80 wt %) in NiMo alloy

is higher than W (60 wt %) in NiW

alloy

For NiMo j for Ni and Mo ↑@ -E>5 V


density for Mo and Ni in NiMo alloy vs potential

1.5

2

2.5

3

3.5

4

0 1 2 3 4 5 6 7

Lo

g o

f p

arti

al c

urr

ent

den

sity

[A/c

m2

]


Mo

Ni

0

1

2

3

4

5

1 2 3 4 5 6 7Par

tial

cu

rren

t d

ensi

ty, m

A/c

m2


Ni

Mo

0

10

20

30

40

50

60

70

80

90

0 100 200 300 400 500 600 700 800

Co

mp

on

ent

con

ten

t, w

t %


Mo

Ni

17

The influence of pH and trisodium citrate concentration

0.5 M of Cit

0.375 M of Cit

0

10

20

30

40

50

60

70

80

90

Mo

83.3

16.7

81.1

18.9

Co

mp

on

ent

con

ten

t, w

t %

Alloy component

Ni

Fig. 28. Dependence of Mo and Ni

content on trisodium citrate

concentration when depositing NiMo

alloy. pH 7.0. Current density

100 mA/cm2

Fig. 29. Dependence of Mo and Ni

content on pH when depositing NiMo

alloy. Current density 100 mA/cm2

pH and Cit concentration do not

influence Mo content in NiMo

significantly, but lower pH (5)

provides higher current efficiency

0

20

40

60

80

100

3 4 5 6 7 8 9

Co

mp

on

ent

con

ten

t, w

t %

pH

Mo

Ni

18

Results

Part II

Electrodeposition of NiW nanowires

Results: NiW nanowires

Ni-W nanowires were deposited using both direct and pulse current

t

-i

t = 0 t

-i

t = 0 t

-i

t = 0

~~

t

-i

t = 0

~~

Direct current-time profile Pulse current-time profile

Time-on

Time-off 0

Applied current density -30...35mA/cm2

Applied current -9.82mA

Frequency

f=1/time-on

Duty cycle

γ=time-on/(time-on+time-off)

19

Dependences for Ni-W thin films were used to find conditions for nanowire deposition

0

10

20

30

40

50

60

70

0 10 20 30 40 50 60

Co

mp

on

ent

con

ten

t, w

t %

Cu

rren

t ef

fici

ency

, %


Ni

Current efficiency

W

Fig. 7. Dependence of W and Ni

content in NiW alloy and current

efficiency on applied current

density

Results: Deposition under direct current

20

Ni-W nanowire morphology turns out to be bumpy (pore shape? Effect of

deposition conditions?)

“Stated” diameter 100 nm - the actual diameter 90-250 nm

Bumps dimensions: width 57-60 nm, height 20-50 nm

Average tungsten content is lower than in thin films (up to 60 wt %)

Fig. 30. Sample 16: d=100 nm, DC, ω(W)=52.4±0.2 wt.%

15

Results: SEM images

Fig. 40. Sample 16: d=100 nm,

DC, ω(W)=52.4±0.2 wt.%

Scanning electron microscopy has

proven the bumpy morphology of the

nanowires deposited under direct

current

21

Results: SEM images

Fig. 41. Sample 16: d=100 nm, DC,

ω(W)=52.4±0.2 wt.%

22

From SEM: bumps width 140 nm

From AFM: bumps width 57-60 nm

Fig. 42. Sample 5: d=100 nm, PC, ton=1 s, toff=1.5 s, ω(W)=49.6±0.7 wt %

23

Results: Deposition under pulse current


Tungsten content is lower than in thin films and when using

DC (52.4±0.2 wt.%)


Fig. 43. Sample 7: d=50 nm, PC, ton=1 s, toff=1.5 s, ω(W)=50.4±0.5 wt.%

“Stated” membrane diameter 50 nm – actual 60-160 nm


Tungsten content is lower than in thin films (up to 60 wt.%),

similar to that for 100 nm pore membrane PC (49.6±0.7 wt.%)

24


25

Fig. 44. Sample 13: d=10 nm, PC, ton=1 s, toff=1.5 s, ω(W)=33.0±2.5 wt.%

“Stated” membrane diameter 10 nm – actual 35-40 nm


Ni-W nanowires of this diameter are less mechanically robust: few are broken

Tungsten content is lower than in thin films (up to 60 wt.%) and that for 100 and 50 nm

pore membranes (49.6±0.7 and 50.4±0.5 wt.%): pH effect? Porosity? (different membrane

though)

Results: Variation in nanowire dimensions with change of

membrane diameter

26

Conclusions: 1. the bigger diameter – the bumpier structure

2. effect is not defined by the diameter only

Deposition mode Pulse current Direct

current

“Stated” membrane

diameter, nm 10 PC 50 PC 100 PC 100 DC

Actual nanowire

diameter, nm 35-40 60-160 70-245 90-250

Bump width, nm 15-16 20-40 91-94 57-60

Bump height, nm 6-7 17-21 23-29 20-50

Tungsten content, wt.% 33±2.5 50.4±0.5 49.6±0.7 52.4±0.2

Deposition time, hours 1.7 5.0 5.7 2.3

Results: Deposition under pulse current – different current frequency

Fig. 45. Sample 32: d=100 nm, ton=10 s,

toff=15 s, f=0.04Hz

Fig. 46. Sample 35: d=100 nm, ton=100 s,

toff=150 s, f=0.004Hz

27

Results: Variation in nanowire dimensions with change

of current frequency

Conclusion: The increase in frequency leads to the increase of

bump width and height

28

On-time/Off-time, s/s ∞ 100/150 10/15 1/1.5

Current frequency, Hz 0 (DC) 0.004 0.04 0.4

Bump width, nm 57-60 73-78 85-89 91-94

Bump height, nm 23-46 6-16 8-20 16-29

Tungsten content, wt % 52.4±0.2 51.5±0.8 54.0±1.5 49.6±0.7

Deposition time, hours 2.3 5.2 5.1 5.7

Results

Part III

Mechanical Robustness of NiW nanowires

Mechanical robustness of NiW nanowires from 100 nm membrane made by DC

Fig. 47b. TEM image of NiW nanowires

after ultrasonic treatment. Membrane:

Whatman Polycabonate 100 nm. Direct

current I=9.82 mA. Tungsten content

52.4 wt %

Fig. 47a. TEM image of NiW nanowires

without ultrasonic treatment. Membrane:



52.4 wt %

29

Mechanical robustness of NiW nanowires from 100 nm membrane made by PC

Fig. 48a. TEM image of NiW nanowires


Whatman Polycabonate 100 nm. Pulse

current I=9.82 mA, ton=1 s, toff=1.5 s.

Tungsten content 49.6 wt %

Fig. 48b. TEM image of NiW nanowires after

ultrasonic treatment. Membrane: Whatman

Polycabonate 100 nm. Pulse current

I=9.82 mA, ton=1 s, toff=1.5 s. Tungsten content

49.6 wt %

30

0

0.2

0.4

0.6

0.8

1

0 0.04

0.11

0 0 0.04

1

No

rmal

ized

qu

anti

ty o

f N

iW

nan

ow

ires

w

ith

len

gth

of

x

≤500nm 0.5-1µm 1-2µm 2-3µm 3-4µm 4-5µm 5-6µm

Fig. 49. Normalized quantity of

NiW nanowires with the length of

x after ultrasonic treatment.

Membrane: Whatman

Polycabonate 100 nm. Direct

current I=9.82 mA. Tungsten

content 52.4 wt %

Comparison: NiW nanowires from 100 nm membrane made by DC and PC after US

0

0.2

0.4

0.6

0.8

1

0 0 0

0.11

0 0.04

1

No

rmal

ized

qu

anti

ty o

f N

iW

nan

ow

ires

wit

h l

eng

th o

f x

≤500nm 0.5-1µm 1-2µm 2-3µm 3-4µm 4-5µm 5-6µm

Fig. 50. Normalized quantity of

NiW nanowires with the length of

x after ultrasonic treatment.

Membrane: Whatman

Polycabonate 100 nm. Pulse

current I=9.82 mA, ton=1 s,

toff=1.5 s. Tungsten content 49.6

wt %

Both made by DC and PC, NiW

nanowires from 100 nm

withstand US treatment

31


Fig. 51a: TEM image of NiW nanowires



current I=9.82 mA. Tungsten content 54.6

wt %

Fig. 51b: TEM image of NiW nanowires




wt %

32












33

0.0

0.2

0.4

0.6

0.8

1.0

0.43

0.29

1.00

0.71

0.57 0.57

No

rmal

ized

qu

anti

ty o

f N

iW

nan

ow

ires

wit

h l

eng

th o

f x

≤500nm 0.5-1µm 1-2µm 2-3µm 3-4µm 4-5µm

Comparison: NiW nanowires from 100 nm and 50 nm membrane made by DC

NiW nanowires from 50 nm

membrane break more than those

from 100 nm membrane

0

0.2

0.4

0.6

0.8

1

0 0.04

0.11

0 0 0.04

1

No

rmal

ized

qu

anti

ty o

f N

iW

nan

ow

ires

w

ith

len

gth

of

x

≤500nm 0.5-1µm 1-2µm 2-3µm 3-4µm 4-5µm 5-6µm

Fig. 54: Normalized quantity of NiW

nanowires with the length of x after

ultrasonic treatment. Membrane:



content 54.6 wt %

Fig. 53: Normalized quantity of NiW

nanowires with the length of x after

ultrasonic treatment. Membrane:



52.4 wt %

34




OsmonicsInc Polycabonate 10 nm. Direct


35.2wt %





wt %

35




OsmonicsInc Polycabonate 10 nm. Pulse








36

Comparison: NiW nanowires from 10 nm membrane made by DC and PC

0.0

0.2

0.4

0.6

0.8

1.01.00

0.67

0.58

0.25

0.08

0.33

0.58

No

rmal

ized

qu

anti

ty o

f N

iW

nan

ow

ires

wit

h l

eng

th o

f x

≤500nm 0.5-1µm 1-2µm 2-3µm 3-4µm 4-5µm 5-6µm

Fig. 57: Normalized quantity of

NiW nanowires with the length

of x after ultrasonic treatment.

Membrane: OsmonicsInc

Polycabonate 10 nm. Direct


content 35.2 wt %

0

0.2

0.4

0.6

0.8

1

0.33

0.22

1.00

0.22

0.11 0.11

0.56

No

rmal

ized

qu

anti

ty o

f N

iW

nan

ow

ires

wit

h l

eng

th o

f x

≤500nm 0.5-1µm 1-2µm 2-3µm 3-4µm 4-5µm 5-6µm

Fig. 58: Normalized quantity of

NiW nanowires with the length

of x after ultrasonic treatment.

Membrane: OsmonicsInc

Polycabonate 10 nm. Pulse

current I=9.82 mA, ton=1 s,

toff=1.5 s. Tungsten content

33.0 wt %

NiW nanowires made by DC

break more than those made

by PC

37

Comparison: NiW nanowires from 10 nm membrane made by DC and PC

Fig. 59: TEM image of NiW nanowires




35.2wt %

Fig. 60: TEM image of NiW nanowires





38

Thin Films

NiW

• Deposit concentration of W in NiW is in a similar range (40-60 wt %) as other

literature reports (@ low –E)

• Our work shows that the iW has an unusual feature, increasing with –E, and then

decreasing, and increasing again at extremely high –E

NiWMo

• In an electrolyte of 1:1 MoO42-:WO4

2-, there is more Mo than W deposited

• The sum of Mo+W in the deposit exceeds the amount of W in NiW

NiMo

• Mo deposit content in NiMo is higher than W deposit content in NiW

Nanowires

• Nanowires grow with a bumpy morphology even under DC

• Their ease to break depends on

• Wire diameter

• DC vs Pulse (pulse deposition is better)

Conclusions

39

Acknowledgments

Scientific adviser: prof. Elizabeth J. Podlaha-Murphy

Committee members: Prof. Mukerjee and Prof. Goluch

William Fowle (TEM/SEM imaging)

Labmates: Alex Avekians, Mehdi Zamanpour,

Hana Kim, Savidra Lucatero,

Shaopeng Sun, Salem Zahmi

Chemical Engineering Department

College of Engineering

Northeastern University

Fulbright Association

40

Thank you for your attention!

Electrodeposition of NiW, NiWMo, and NiMo Alloy Thin Films ...Electrodeposition of NiW, NiWMo, and...

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